While many of his contemporaries have already retired, Duncan continues to produce at an All-Star level (he made his 14th All-Star team last season).

Now heading into his 17th NBA season, Duncan has somehow found a way to avoid a steep decline in any area of his game. Not only that, but "The Big Fundamental" is just as important as he ever has been to his team's fate.

Last season, Duncan was the 2nd best player on a Spurs team that came within an offensive rebound of winning an NBA title. Considering Duncan is 37 it's fair to question whether the Spurs can make another run. After all, the last team to win a title with a 37 year old among it's top 2 players (in terms of PER) were the 2003 Spurs who had David Robinson as their 2nd best player, behind Duncan of course.

But the Spurs will break that mold and compete for a championship for several reasons. One of those reasons is Tony Parker, and another is Gregg Popovich. However, the biggest reason of all is Tim Duncan's refusal to age in a normal manner. Let's take a closer look.

While Duncan plays less than he did in his prime, he has amazingly maintained an elite level of production (17.8 PPG, 9.9 RPG, 2.7 BPG last season). In fact, in terms of his per-36 minute stats (what he averaged per-36 minutes of playing time, a good way to see if a player really has improved or declined, or if their simply receiving more or less playing time) he hasn't dipped at all.

Take a look.

2012-13

Career High

Career Average

PPG

21.3

22.6

20.7

RPG

11.9

12.2

11.5

APG

3.2

3.8

3.1

BPG

3.2

3.2

2.3

Usage rate

27.8%

29.7%

27.7%

PER

24.4

27.1

24.7

As you can see, Duncan was above his career averages in everything except Player Efficiency Rating (PER), and that was only off by 0.3.

He also set a new career high in blocks per-36 minutes and approached career highs in just about everything else.

Popovich has discovered that as long as he plays Duncan only 30 minutes a night and rests him from time to time, he can still be every bit as productive as he was 10 years ago.

But that doesn't mean his game hasn't changed. Because it has.

Duncan, like many great players, has found a way to adapt his game to maintain his effectiveness. For example, the way Duncan acts when he gets the ball in the post has changed dramatically from his athletic prime until now.

To illustrate that, let's take a look at a few of Duncan's post ups from the 2003 playoff run, when he was at his absolute pinnacle (he averaged 24.7 PPG, 15.4 RPG, 5.3 APG and 3.3 BPG as the Spurs won their second title).

As you can see, 27 year old Duncan took the ball directly to the rim, using his quick first step and brute strength to simply overpower Horry. There wasn't a huge need to be crafty because he was so much better than the rest of the players on the court.

However, times change.

Now let's take a look at a few post possessions that took place in this year's NBA Finals against the Heat. You'll notice, the end result is the same: two points for San Antonio. But that's the only similarity.

First, there was this move during Game 7, where Duncan decides against taking it up, and instead dishes to Boris Diaw.

Duncan vs the Heat in the 2013 Finals

One of the major differences between 2003 Duncan and 2013 Duncan is how much slower his first step is now. This makes it harder for him to get position on his man and means he gets pushed out of the paint more often than he did a decade ago.

In the last clip, he overcomes the fact that Chris Bosh pushes him out of the paint by finding an open Diaw. In this next one, he again can't get by Bosh, but this time he's able to show off his range a bit.

Duncan vs the Heat in the 2013 Finals, Part 2

After watching these clips, it's clear that it is now more difficult for Duncan to score from the block than it was in the past. Sure, he can still do it. But it's no longer as efficient a call for the Spurs to simply dump it to him in the block.

Instead, the Spurs now use Duncan in a different way, cutting down on the number of post-ups and isolation plays they run for him, and instead using him in more pick-and-roll and back cuts to the hoop. This takes some pressure off of the Spurs elder statesman as he relies less on his one-on-one skills, and more on his teammates to help create his shot.

Here's some data to backup what our eyes are telling us. By using Synergy Sports, which tracks every player's usage pattern and production dating back to the 2009-10 season, we can compare Duncan from 2009-10 (at age 32) to the Duncan from last season (at age 36).

While it's not ideal that Synergy only goes back four years, it still should help us figure out if Duncan really has altered his game like it appears he has.

Here's the breakdown:

2009-10

2012-13

Isolation

7.1%

6.3%

Post-up

42.8%

28.5%

Pick-and-Roll (non-ball handler)

16.2%

20.6%

Cut

8.8%

12.3%

So Duncan has seen a decrease in the types of plays that utilize his one-on-one skills, and he's seen an increase in the types of plays that rely on ball movement. Just about exactly what you'd expect from a guy as he moves from his early 30s to his late 30s.

This is great news for the Spurs.

While Duncan is not about to gain any athleticism back, there is no reason to believe that one of the best players of all time will abruptly fall off when it comes to his pick-and-roll production.

Of course, all players eventually hit a wall. But those who can adapt to their ever changing skill-set are far more likely to continue playing at an elite level for longer. That's exactly what Duncan has done.

That means that the Spurs should be able to count on similar production this year from both Duncan and Parker (who's only 31), and improvement from their 3rd best player in Kawhi Leonard.

That should help the aging Spurs keep that championship window open for at least one more season.